Powder pump for conveying coating powder

ABSTRACT

The invention relates to a powder pump ( 100; 100 ′) for conveying coating powder, the powder pump ( 100; 100 ′) having a powder chamber ( 10; 10 ′) with a casing tube ( 1; 1 ′) and a gas-permeable filter element ( 2; 2 ′) arranged inside the casing tube ( 1; 1 ′) a first pinch valve ( 3; 3 ′), connected to the intake-side end region of the powder chamber ( 10; 10 ′), and a second pinch valve ( 4; 4 ′), connected to the delivery-side end region of the powder chamber ( 10; 10 ′). In order to achieve the effect that the powder pump ( 100; 100 ′) can be maintained with relatively little effort, according to the invention a first connection element ( 6; 6 ′) is provided, connected to the first pinch valve ( 3; 3 ′) and fitted onto or inserted into the intake-side end region of the powder chamber ( 10; 10 ′). A second connection element ( 7; 7 ′) is also provided, connected to the second pinch valve ( 4; 4 ′) and fitted onto or inserted into the delivery-side end region of the powder chamber ( 10; 10 ′).

The present invention relates to a powder pump for conveying coatingpowder according to the preamble of independent patent claim 1.

Accordingly, the invention relates to a powder pump which has a powderchamber with a preferably cylindrical and in particularcircular-cylindrical casing tube and a gas-permeable filter elementarranged inside the casing tube, with furthermore a first pinch valve,connected to the intake-side end region of the powder chamber, and asecond pinch valve, connected to the delivery-side end region of thepowder chamber, being provided, and with the powder chamber having atleast one connection for alternately creating a positive pressure and anegative pressure in the powder chamber.

Such a powder pump is known in principle from the prior art. Forexample, document EP 1 551 558 A1 discloses a powder pump which has afirst powder chamber and a second powder chamber, arranged parallel tothe first powder chamber. The powder chambers of the powder pump knownfrom this prior art are respectively bounded both on the intake side andon the delivery side by a mechanically actuated pinch valve arrangement.

To be specific, it is in this case provided that, in the intake-side anddelivery-side regions of the powder pump, the powder hoses connected tothe respective powder chambers can be deformed by a mechanicallyactuated rod in order to pinch off or open the hose portion as and whenrequired. The powder chambers of the known pump also each have agas-permeable filter element. A negative pressure can be set in thepowder chambers separately from each other by way of a vacuumconnection, as a result of which coating powder can be sucked into thepowder chamber by way of the intake-side end region of the respectivepowder chamber. Subsequently, the pinch valve provided at theintake-side end region of the powder chamber is closed and the pinchvalve provided at the delivery-side end region of the powder chamber isopened. The presence of a positive pressure in the powder chamber hasthe effect that the coating powder previously sucked into the powderchamber is again discharged from the powder chamber by way of thedelivery-side end region.

It has been found in practical use that a powder pump of the typedescribed above has various disadvantages, in particular with regard toits maintenance. In particular, in the case of the known powder pump, apossibly clogged filter element can only be exchanged with relativelygreat effort, since virtually the complete powder pump has to beunscrewed for this purpose. In particular, the solution known from thisprior art does not allow a filter element to be exchanged withoutinterfering with the structure of the pinch valves. There isconsequently the risk of leakages occurring after maintenance or theexchange of the filter element, so that dependable functioning of thepowder pump is no longer ensured.

On the basis of these problems, the present invention is based on theobject of developing a powder pump of the type mentioned at thebeginning, and as known for example from the document EP 1 551 558 A1,to the extent that it can be maintained with relatively little effort,it being possible in particular for the gas-permeable filter element ofthe powder chamber to be exchanged without the risk of impairing thefunctioning of the pump.

This object is achieved by the subject matter of independent patentclaim 1. Advantageous developments are specified in the dependent patentclaims.

In particular, in the case of the solution according to the invention,it is provided that—as a difference from the solution known from theprior art—the intake-side and delivery-side pinch valves of the powderpump are not directly connected to the powder chamber. Rather, thesolution according to the invention uses a connection element, which isconnected to the first (intake-side) pinch valve and is fitted onto orinserted into the intake-side end region of the powder chamber. Alsoused is a second connection element, which is connected to the second(delivery-side) pinch valve and is fitted onto or inserted into thedelivery-side end region of the powder chamber.

In addition, the solution according to the invention has a mount inorder to receive the powder chamber with the connection elements fittedon or inserted in on both sides. To allow secure fixing of theconnection elements fitted on or inserted in on both sides, alsoprovided is an arresting mechanism, with which the connection elements,fitted onto or inserted into the powder chamber on both sides, arearrested in relation to the mount when the powder chamber with theconnection elements fitted on or inserted in on both sides has beenreceived by the mount.

The advantages that can be achieved by the solution according to theinvention are obvious: the fact that the corresponding connectionelements that are connected to the intake-side pinch valve and thedelivery-side pinch valve are fitted onto or inserted into thecorresponding end region of the powder chamber means that—for examplefor the purpose of maintenance—the powder chamber can be separated fromthe connection elements, and consequently from the corresponding pinchvalves, by simply releasing this fitted or inserted connection.Specifically, with the solution according to the invention it ispossible in a simple way, for example when exchanging the gas-permeablefilter element arranged in the powder chamber, to release the fitted orinserted connection between the corresponding connection element and thepowder chamber. The powder chamber with the filter element receivedtherein is subsequently separate from the intake-side and delivery-sidepinch valves.

In order that no powder can escape from the fitted or insertedconnections during operation of the powder pump, and consequently inparticular that the connection elements fitted on or inserted in on bothsides are securely fixed to the powder chamber, it is provided accordingto the invention that the connection elements fitted onto or insertedinto the powder chamber on both sides are arrested in relation to themount when the powder chamber with the connection elements fitted on orinserted in on both sides has been received by the mount.

In a preferred implementation of the solution according to theinvention, serving as the arresting mechanism are a first bolt,connected to the first connection element and protruding radially fromthe first connection element, and a second bolt, connected to the secondconnection element and protruding radially from the second connectionelement. These two bolts can each be received in a longitudinal slit,provided in the mount and running perpendicularly to the longitudinaldirection of the powder chamber. In this way it is ensured that the twoconnection elements fitted onto or inserted into the powder chamber onboth sides cannot move in the longitudinal direction in relation to thepowder chamber when the powder chamber with the connection elementsfitted on or inserted in on both sides has been received by the mount,and in particular when the first bolt, protruding radially from thefirst connection element, and the second bolt, protruding radially fromthe second connection element, have been received in the correspondinglongitudinal slit provided in the mount.

In a preferred development of the last-mentioned embodiment, it isprovided that the arresting mechanism has two first bolts, which arearranged diametrically in relation to each other, are each connected tothe first connection element and each protrude radially from the firstconnection element, the mount having two first longitudinal slits foreach receiving one of the two first bolts.

Alternatively or in addition to this, it is conceivable that thearresting mechanism has two second bolts, which are arrangeddiametrically in relation to each other, are each connected to thesecond connection element and each protrude radially from the secondconnection element, the mount having two second longitudinal slits foreach receiving one of the two second bolts.

The arresting of the connection elements fitted on or inserted in onboth sides in relation to the powder chamber can be further improved ifthe end of the first longitudinal slit is adjoined at right angles by ashort transverse slit or if the end of the second longitudinal slit isadjoined at right angles by a short transverse slit. In this way it canbe effectively prevented that the powder chamber with the two connectionelements fitted onto or inserted into the powder chamber on both sidescan slide out of the longitudinal slits again.

Of course, further solutions also come into consideration for thespecific configuration of the arresting mechanism. In particular, it isalso conceivable that on the mount itself there are provided radiallyprotruding bolts which engage in corresponding longitudinal slits thatare formed respectively in the first and second connection elements.

With the configuration of the powder chamber described above and theconnection elements fitted on or inserted in on both sides it is on theone hand ensured that the connection elements are securely fixed inrelation to the powder chamber during the operation of the powder pump,and in particular whenever the powder chamber with the connectionelements fitted on or inserted in on both sides has been received in themount. To exchange the filter element received in the powder chamber, itis merely required to take the powder chamber with the connectionelements fitted on or inserted in on both sides out of the mount, thearresting of the connection elements being released at the same time.Consequently, taking the powder chamber out allows the connectionelements fitted on or inserted in at the end regions of the powderchamber to be pulled out, in order thereby to release the fitted on orinserted in connection. The filter element can subsequently be exchangedwithout any problem. The subsequent installation of the powder chamberis performed in the reverse sequence.

In order to simplify not only the exchange of the filter element butalso the maintenance of the pinch valves that are used in the case ofthe powder pump, it is provided in an advantageous development of thesolution according to the invention that the first connection elementhas a stub-like region, facing the powder chamber, and a taperingregion, facing the first pinch valve and tapering conically in thedirection of the first pinch valve, the stub-like region of the firstconnection element being fitted onto or inserted into the intake-sideend region of the powder chamber and the conically tapering region ofthe first connection element being connected to the first pinch valve.

Alternatively or in addition to this, it is conceivable that the secondconnection element also has a stub-like region, facing the powder pump,and a tapering region, facing the second pinch valve and taperingconically in the direction of the second pinch valve, the stub-likeregion of the second connection element being fitted onto or insertedinto the delivery-side end region of the powder chamber and theconically tapering region of the second connection element beingconnected to the second pinch valve.

Preferably, in the case of the aforementioned embodiments of the powderpump according to the invention, the stub-like region of the first orsecond connection element and the tapering region of the first or secondconnection element, tapering conically in the direction of thecorresponding pinch valve, are inserted in each other and releasablyarrested in relation to each other, preferably with the aid of a screw.

To exchange one or both pinch valves, it is accordingly merely requiredto release the arrestment between the stub-like region of thecorresponding connection element and the conically tapering region ofthe connection element, the stub-like region of the connection elementremaining firmly connected to the powder chamber and it being possiblefor the conically tapering region of the connection element togetherwith the pinch valve that is to be maintained or exchanged to bereleased from the powder pump.

With regard to the configuration of the pinch valves that are used inthe case of the powder pump according to the invention, it is ofadvantage if each pinch valve has a pinch valve housing with aninlet-side flange region and an outlet-side flange region as well as anelastically deformable valve element, preferably in the form of a hoseportion. In this case, the valve element should be arranged inside thepinch valve housing in such a way that the inlet of the pinch valve canbe brought into fluidic connection with the outlet of the pinch valve byway of the valve element formed as a hose portion.

It is of advantage here if the pinch valve housing has at least oneconnection for feeding compressed air as and when required into thespace formed between the inner wall of the pinch valve housing and thevalve element arranged inside the pinch valve housing. When feeding incompressed air, a positive pressure is formed in the space between theinner wall of the pinch valve housing and the valve element, as a resultof which the valve element is pressed together in the radial directionand the pinch valve is closed. If the pressure in the pinch valvehousing is subsequently relieved, the valve element resumes its initialstate, so that there is a fluidic connection between the inlet of thepinch valve and the outlet of the pinch valve by way of the valveelement.

In a preferred implementation of the solution according to theinvention, it is conceivable here that the pinch valve housing has atleast one connection for creating a negative pressure as and whenrequired inside the pinch valve housing. In this way, the opening timeof the pinch valve can be reduced.

The invention is not restricted to the powder pump described above assuch, but also includes an arrangement comprising a powder pump of thetype described above and a further identical powder pump. Thisarrangement forms a coating powder conveying device.

Each powder pump of the coating powder conveying device has at least onegas path, by which the powder chamber can be connected alternately to avacuum line, for sucking coating powder into the powder chamber throughthe open powder-inlet valve while the powder-outlet valve is closed, orto a compressed-air line, for pneumatically discharging a portion ofpowder present in the powder chamber through the open powder-outletvalve while the powder-inlet valve is closed. The two powder pumps canbe alternately switched over to sucking in and discharging powder, itbeing possible alternately to switch the one pump to intake and theother substantially at the same time to discharge in a first operatingphase, and then to switch the one pump to discharge and the othersubstantially at the same time to intake in a second operating phase.

In the case of a preferred embodiment of the coating powder conveyingdevice, the gas path contains a suction-air opening and a compressed-airopening in a circumferential housing wall of the powder chamber, amicroporous filter tube, which, at least over part of the length orpreferably the entire length of the powder chamber, forms thecircumferential wall of the powder chamber between the powder inlet andthe powder outlet and separates the powder chamber from an annularchamber. The annular chamber is formed between the outer circumferenceof the filter tube and the inner circumference of the circumferentialhousing wall and surrounds the filter element formed as a filter tube.The filter tube is permeable to air, but not to coating powder onaccount of its small pore size. It preferably consists of a sinteredmaterial. The suction-air opening preferably opens out into the annularchamber near to the powder outlet, and the compressed-air openingpreferably opens out into the annular chamber near to the powder inlet.

For connecting the suction-air opening and the compressed-air opening tothe suction-air line and the compressed-air line, respectively, and forconnecting the powder-inlet valve and the powder-outlet valve of the twopowder pumps alternately to the compressed-air line and the outsideatmosphere and/or a suction line, a valve device or pneumaticsubassembly, which has for example two valves and can be controlled by acontrol device, may be provided.

Exemplary embodiments of the powder pumps according to the invention aredescribed in more detail below with reference to the accompanyingdrawings, in which:

FIG. 1 shows a schematic representation of a coating powder conveyingdevice with two powder pumps arranged parallel to each other accordingto an exemplary embodiment of the present invention;

FIG. 2 shows a perspective view of the internal structure of a coatingpowder conveying device with two powder pumps arranged parallel to eachother according to an exemplary embodiment of the present invention;

FIG. 3 shows a perspective view of the two powder pumps arrangedparallel to each other of the coating powder conveying device accordingto FIG. 2, each in the state in which they have been received in theassociated powder chamber mount;

FIG. 4 shows a longitudinal sectional view of part of a powder pump usedin the case of the coating powder conveying device according to FIG. 2;

FIG. 5 a shows an exploded representation of one of the two powder pumpsthat are used in the case of the coating powder conveying deviceaccording to FIG. 2; and

FIG. 5 b shows a perspective view of one of the two powder pumps thatare used in the case of the coating powder conveying device according toFIG. 2.

Initially only with reference to the representation in FIG. 1, adescription is given below of the functioning of a coating powderconveying device in which two powder pumps 100, 100′ arranged parallelto each other according to an exemplary embodiment of the presentinvention are used.

As schematically represented in FIG. 1, each of the two powder pumps100, 100′ arranged parallel to each other has a powder chamber 10, 10′,which is formed by a cylindrical, in particular circular-cylindrical,casing tube 1, 1′ and a filter element 2, 2′ received inside the casingtube. Each powder chamber 10, 10′ has a powder inlet 30, 30′ with apowder-inlet valve 3, 3′ and a powder outlet 31, 31′ with apowder-outlet valve 4, 4′. The respective powder-inlet valves 3, 3′ arealso referred to hereafter as “first valves” or “intake-side valves”.The powder-outlet valves 4, 4′ are referred to as “second valves” or“delivery-side valves”.

During the intake process, a vacuum (negative pressure) is generated inthe powder chamber 10, 10′ of the powder pump 100, 100′. This negativepressure sucks the coating powder into the powder chamber 10, 10′ by wayof the corresponding powder inlet 30, 30′. The fine-porous filterelement 2, 2′ in the powder chamber 10, 10′ separates the powder. Duringthe intake process, the powder chamber 10, 10′ is connected to theoutput side or delivery side B by the delivery-side valve 4, 4′.

During the conveying process, on the other hand, the intake-side valve3, 3′ on the powder inlet side A of the powder chamber 10, 10′ isclosed, while the delivery-side valve 4, 4′ is opened. The coatingpowder previously sucked into the powder chamber 10, 10′ during theintake process is then forced out of the powder chamber 10, 10′ andfurther conveyed by means of positive pressure, which is built up bycompressed air through the fine-porous filter element 2, 2′.

As the representation in FIG. 1 reveals, the intake process andconveying process alternate between the two powder pumps 100, 100′arranged parallel to each other.

With reference to the representations in FIGS. 2 to 5, there follows adescription of an exemplary embodiment of a coating powder conveyingdevice in which two powder pumps 100, 100′ arranged parallel to eachother according to an embodiment of the present invention are used.

Specifically, FIG. 2 shows in a perspective view the internal structureof a coating powder conveying device with two powder pumps 100, 100′arranged parallel to each other according to an exemplary embodiment ofthe present invention. The coating powder conveying device has twopowder pumps 100, 100′, each of the two powder pumps 100, 100′ having apowder chamber 10, 10′ with a cylindrical and in particularcircular-cylindrical casing tube 1, 1′ and a gas-permeable filterelement 2, 2′ arranged inside the casing tube 1, 1′. The filter element2, 2′ is preferably a rigid body of sintered material, preferably ofsintered metal, for example bronze or aluminum, or sintered plastic or asintered material mixture.

Respectively provided at the powder inlet of each powder pump 100, 100′is a first pinch valve 3, 3′, connected to the intake-side end region ofthe powder chamber 10, 10′. A second pinch valve 4, 4′ is connected tothe respective delivery-side end region of the powder chamber 10, 10′.

Although in the case of the exemplary embodiment pinch valves arerespectively used as the powder-inlet and powder-outlet valves, they maybe of any kind desired.

In the case of the embodiment represented, the powder-inlet side of thetwo first (intake-side) pinch valves 3, 3′ are connected by way ofsupply-line branches 70 c, 70 b of a Y connecting piece 70 to a powdersupply line, which leads for example to a powder container (notexpressly represented in FIG. 2). For this purpose, hose connectors 75are used, in order to connect the powder-inlet side of the two firstpinch valves 3, 3′ to the supply-line branches 70 c, 70 b of the Yconnecting piece 70.

However, instead of a Y connecting piece 70, it is also conceivable toconnect the respective powder-inlet sides of the first (intake-side)pinch valves 3, 3′ to a powder container or to two different powdercontainers by way of separate powder supply lines.

In the case of the embodiment represented, the powder outlets of the twosecond (delivery-side) pinch valves 4, 4′ are connected bydischarge-line branches 71 c, 71 b, for example of a Y-shaped lineconnecting piece 71, to one end of a powder discharge hose, the otherend of which opens out in a further powder container (not represented).The powder discharge line may be a rigid pipeline, but is preferably aflexible hose.

In the case of the embodiment represented in FIG. 2, the powder chambers10, 10′ of the two powder pumps 100, 100′ arranged parallel to eachother are each received in a mount 8, 8′ and arrested there. The mannerin which the powder chambers 10, 10′ are arrested and received in therespective mounts 8, 8′ is described in more detail with reference tothe following drawings.

The representation in FIG. 2 also reveals that the exemplary embodimentof the coating powder conveying device has a pump controller 50 and apneumatic group 51 that can be activated by the pump controller 50, inorder to operate the two powder pumps 100, 100′ arranged parallel toeach other in phase opposition according to the functional principledescribed above with reference to FIG. 1.

With reference to the representations in FIGS. 3 to 5, there follows amore detailed description of the structure of each powder pump 100, 100′that is used in the case of the coating powder conveying deviceaccording to FIG. 2.

As revealed in particular by the representation in FIG. 5 a, which showsan exploded representation of a powder pump 100 or 100′, each powderpump 100, 100′ has a casing tube 1, 1′, inside which a gas-permeablefilter element 2, 2′ is arranged. The casing tube 1, 1′ with the filterelement 2, 2′ received inside it forms the powder chamber 10, 10′ of thecorresponding powder pump 100, 100′.

Provided at the intake-side end region of the powder chamber 10, 10′ isa first (intake-side) pinch valve 3, 3′. A second (delivery-side) pinchvalve 4, 4′ is connected to the delivery-side end region of therespective powder chamber 10, 10′.

In the case of the representation in FIG. 5 a, the first (intake-side)pinch valve 3, 3′ is shown in the assembled state, while the second(delivery-side) pinch valve 4, 4′ is likewise shown in an explodedrepresentation. The structure and the functioning of the first andsecond pinch valves 3, 3′; 4, 4′ are identical in the embodimentrepresented.

Accordingly, each pinch valve 3, 3′; 4, 4′ has a pinch valve housing 21,21′ with an inlet-side flange 22, 22′ and an outlet-side flange 23, 23′.An elastically deformable valve element 24, 24′ is received in the pinchvalve housing 21, 21′. This elastically deformable valve element 24, 24′is specifically an elastically deformable hose portion. Each flange 22,22′; 23, 23′ has a hose connection 77, to which a powder hose can beconnected.

As the representation in FIG. 4 reveals, in the case of each pinch valve3, 3′; 4, 4′ the valve element 24, 24′ is arranged inside the pinchvalve housing 21, 21′ in such a way that the inlet of the pinch valve 3,4; 3′, 4′ can be brought into fluidic connection with the outlet of thepinch valve 3, 4; 3′, 4′ by way of the valve element 24, 24′ formed as ahose portion. The pinch valve housing 21, 21′ has a connection 9, 9′, inorder to feed compressed air as and when required into the space 26, 26′formed between the inner wall of the pinch valve housing 21, 21′ and thevalve element 24, 24′ arranged inside the pinch valve housing 21, 21′.When supplying compressed air, the valve element 24, 24′ is elasticallydeformed, so that the fluidic connection between the inlet and theoutlet of the pinch valve is interrupted. If, on the other hand, thereis no compressed air in the intermediate space between the inner wall ofthe pinch valve housing 21, 21′ and the valve element 24, 24′ arrangedinside the pinch valve housing 21, 21′, the previously elasticallydeformed valve element 24, 24′ reverts to its initial state, in whichthere is a fluidic connection between the inlet and the outlet of thepinch valve housing.

A vacuum connection may also be connected by way of the at least oneconnection 9, 9′ of the pinch valve, in order to evacuate the compressedair previously introduced into the intermediate space 26, 26′ for rapidopening of the pinch valve.

As the exploded representation in FIG. 5 a reveals, the inlet-sideflange 22, 22′ and the outlet-side flange 23, 23′ of each pinch valve isrespectively releasably fastened to the pinch valve housing 21, 21′ withthe aid of screws 27. In this way, the pinch valve is configured as acomponent which can be connected to the appropriate powder chamber 10,10′ by way of a corresponding connection element.

Specifically, each powder pump 100, 100′ is provided with a firstconnection element 6, 6′, which is fitted onto or inserted into theintake-side end region of the corresponding powder chamber 10, 10′. Thisconnection element 6, 6′ is connected to the first (intake-side) pinchvalve 3, 3′. In the same way, each powder pump 100, 100′ has a secondconnection element 7, 7′, which is fitted onto or inserted into thedelivery-side end region of the powder chamber 10, 10′ and connected tothe second (delivery-side) pinch valve 4, 4′.

The representation in FIG. 5 a reveals in particular that the firstconnection element 6, 6′ has a stub-like region 16, 16′, facing thepowder chamber 10, 10′, and a tapering region 17, 17′, facing the first(intake-side) pinch valve 3, 3′ and tapering conically in the directionof the first pinch valve 3, 3′. The stub-like region 16, 16′ of thefirst connection element 6, 6′ has in this case been fitted onto orinserted into the intake-side end region of the powder chamber 10, 10′,while the conically tapering region 17, 17′ of the first connectionelement 6, 6′ has been connected to the first pinch valve 3, 3′.

The representation in FIG. 4 reveals that, in the case of the preferredembodiment of the present invention, the stub-like region 16, 16′ of thefirst connection element 6, 6′ and the tapering region 17, 17′ of thefirst connection element 6, 6′, tapering conically in the direction ofthe first pinch valve 3, 3′, are inserted in each other and releasablyarrested in relation to each other, preferably with the aid of at leastone countersunk screw.

In the same way, in the case of the preferred embodiment of the presentinvention it is provided that the second connection element 7, 7′, whichhas been fitted onto or inserted into the delivery-side end region ofthe powder chamber 10, 10′ and connected to the second (delivery-side)pinch valve 4, 4′, has a stub-like region 18, 18′, facing the powderchamber 10, 10′, and a tapering region 19, 19′, facing the second pinchvalve 4, 4′ and tapering conically in the direction of the second pinchvalve 4, 4′, the stub-like region 18, 18′ of the second connectionelement 7, 7′ being fitted onto or inserted into the delivery-side endregion of the powder chamber 10, 10′ and the conically tapering region19, 19′ of the second connection element 7, 7′ being connected to thesecond pinch valve 4, 4′. Specifically, it is in this case preferred ifthe stub-like region 18, 18′ of the second connection element 7, 7′ andthe tapering region 19, 19′ of the second connection element 7, 7′,tapering conically in the direction of the second pinch valve 4, 4′, areinserted in each other and releasably arrested in relation to eachother, likewise preferably with the aid of at least one countersunkscrew 20.

Suitable O-rings 75 are preferably used for sealing the fitted orinserted connections used in the case of the solution according to theinvention.

In order to be able to securely connect the respective connectionelements (first connection elements 6, 6′ and second connection elements7, 7′) to the corresponding powder chambers 10, 10′, it is provided thatthe connection elements 6, 6′; 7, 7′ are respectively fitted onto orinserted into the intake-side or delivery-side end region of the powderchamber 10, 10′. The powder chamber 10, 10′ with the connection elements6, 7; 6′, 7′ fitted on or inserted in on both sides is subsequentlyreceived in a mount 8, 8′. This mount 8, 8′ also serves for arrestingthe connection elements 6, 7; 6′, 7′, fitted onto or inserted into thepowder chamber 10, 10′ on both sides, in relation to the mount 8, 8′when the powder chamber 10, 10′ with the connection elements 6, 7; 6′,7′ fitted on or inserted in on both sides has been received by the mount8, 8′.

In the case of the embodiment represented, used for this purpose are afirst bolt 11, 11′, connected to the first connection element 6, 6′ andprotruding radially from the first connection element 6, 6′, and asecond bolt 12, 12′, connected to the second connection element 7, 7′and protruding radially from the second connection element 7, 7′. Thesebolts 11, 12; 11′, 12′ are received by corresponding longitudinal slits13, 13′, running perpendicularly to the longitudinal direction L of thepowder chamber 10, 10′, when the respective powder chamber 10, 10′ withthe connection elements 6, 7; 6′, 7′ fitted on or inserted in on bothsides is inserted into the mount 8, 8′.

As the representation in FIG. 5 a reveals, the end of the firstlongitudinal slit 13, 13′ is adjoined at right angles by a shorttransverse slit 15, 15′, in order to prevent unintentional sliding outof the powder chamber 10, 10′ received in the mount 8, 8′.

The invention is not restricted to the exemplary embodiments describedabove, but is made up of all the features disclosed herein consideredtogether.

1. A powder pump for conveying coating powder, the powder pump havingthe following: a powder chamber with a preferably cylindrical and inparticular circular-cylindrical casing tube (1; 1′) and a gas-permeablefilter element arranged inside the casing tube; a first pinch valve,connected to the intake-side end region of the powder chamber; and asecond pinch valve, connected to the delivery-side end region of thepowder chamber, the powder pump having at least one connection foralternately creating a positive pressure and a negative pressure in thepowder chamber, wherein a first connection element, which is connectedto the first pinch valve and is fitted onto or inserted into theintake-side end region of the powder chamber; a second connectionelement, which is connected to the second pinch valve and is fitted ontoor inserted into the delivery-side end region of the powder chamber; amount for receiving the powder chamber with the connection elementsfitted on or inserted in on both sides; and an arresting mechanism forarresting the connection elements, fitted onto or inserted into thepowder chamber on both sides, in relation to the mount when the powderchamber with the connection elements fitted on or inserted in on bothsides has been received by the mount.
 2. The powder pump as claimed inclaim 1, the arresting mechanism having a first bolt, connected to thefirst connection element and protruding radially from the firstconnection element, and a second bolt, connected to the secondconnection element and protruding radially from the second connectionelement; and the arresting mechanism also having a first longitudinalslit, provided in the mount and running perpendicularly to thelongitudinal direction of the powder chamber, for receiving the firstbolt, protruding radially from the first connection element, and asecond longitudinal slit, provided in the mount and runningperpendicularly to the longitudinal direction of the powder chamber, forreceiving the second bolt, protruding radially from the secondconnection element.
 3. The powder pump as claimed in claim 2, the end ofthe first longitudinal slit being adjoined at right angles by a shorttransverse slit; or the end of the second longitudinal slit beingadjoined at right angles by a short transverse slit.
 4. The powder pumpas claimed in claim 2, the arresting mechanism having first bolts, whichare arranged diametrically in relation to each other, are each connectedto the first connection element and each protrude radially from thefirst connection element, and the mount having two first longitudinalslits for each receiving one of the two first bolts.
 5. The powder pumpas claimed in claim 2, the arresting mechanism having two second bolts,which are arranged diametrically in relation to each other, are eachconnected to the second connection element and each protrude radiallyfrom the second connection element, and the mount having two secondlongitudinal slits for each receiving one of the two second bolts. 6.The powder pump as claimed in claim 1, the first connection elementhaving a stub-like region, facing the powder chamber, and a taperingregion, facing the first pinch valve and tapering conically in thedirection of the first pinch valve, the stub-like region of the firstconnection element being fitted onto or inserted into the intake-sideend region of the powder chamber and the conically tapering region ofthe first connection element being connected to the first pinch valve.7. The powder pump as claimed in claim 6, the stub-like region of thefirst connection element and the tapering region of the first connectionelement, tapering conically in the direction of the first pinch valve,being inserted in each other and releasably arrested in relation to eachother, preferably with the aid of at least one countersunk screw.
 8. Thepowder pump as claimed in claim 1, the second connection element havinga stub-like region, facing the powder chamber, and a tapering region,facing the second pinch valve and tapering conically in the direction ofthe second pinch valve, the stub-like region of the second connectionelement being fitted onto or inserted into the delivery-side end regionof the powder chamber and the conically tapering region of the secondconnection element being connected to the second pinch valve.
 9. Thepowder pump as claimed in claim 8, the stub-like region of the secondconnection element and the tapering region of the second connectionelement, tapering conically in the direction of the second pinch valve,being inserted in each other and releasably arrested in relation to eachother, preferably with the aid of at least one countersunk screw. 10.The powder pump as claimed in claim 1, the first pinch valve and thesecond pinch valve each having the following: a pinch valve housing withan inlet-side flange and an outlet-side flange; and an elasticallydeformable valve element in the form of a hose portion, the valveelement being arranged inside the pinch valve housing in such a way thatthe inlet of the pinch valve can be brought into fluidic connection withthe outlet of the pinch valve by way of the valve element formed as ahose portion, the pinch valve housing having at least one connection forfeeding compressed air as and when required into the space formedbetween the inner wall of the pinch valve housing and the valve elementarranged inside the pinch valve housing.
 11. The powder pump as claimedin claim 10, the pinch valve housing having at least one connection forcreating a negative pressure as and when required in the space formedbetween the inner wall of the pinch valve housing and the valve elementarranged inside the pinch valve housing.
 12. The powder pump as claimedin claim 10, the inlet-side flange and the outlet-side flange of thepinch valve being respectively releasably fastened to the pinch valvehousing with the aid of screws.
 13. The powder pump as claimed in claim10, the tapering region of the first connection element, taperingconically in the direction of the first pinch valve, being connected tothe outlet of the first pinch valve by way of the outlet-side flange ofthe first pinch valve; and the tapering region of the second connectionelement, tapering conically in the direction of the second pinch valve,being connected to the inlet of the second pinch valve by way of theinlet-side flange of the second pinch valve.
 14. The powder pump asclaimed in claim 1, a control device also being provided, by way ofwhich the first and second pinch valves are activated in such a waythat, in an intake phase of the powder pump, the first pinch valve isopen and the second pinch valve is closed, while at the same time anegative pressure is created in the powder chamber by way of the atleast one connection, and, in a discharge phase of the powder pump, thefirst pinch valve is closed and the second pinch valve is open, while atthe same time a positive pressure is created in the powder chamber byway of the at least one connection.
 15. An arrangement comprising apowder pump as claimed in claim 1 and a further identical powder pump,the arrangement also having a first Y piece for connecting a powderline, in particular a powder hose, both to the inlet of the first pinchvalve of the powder pump and to the inlet of the first pinch valve ofthe further identical powder pump, and a second Y piece also beingprovided, for connecting a powder line, in particular a powder hose,both to the outlet of the second pinch valve of the powder pump and tothe outlet of the second pinch valve of the further identical powderpump.
 16. The arrangement—as claimed in claim 15, the powder pump andthe further powder pump being operated in phase opposition.